1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to a wireless communication terminal capable of changing channels and a channel changing method thereof. More particularly, methods and apparatuses consistent with the present invention relate to a wireless communication terminal capable of changing a communication channel according to environment during the wireless communications so as to avoid interference between receiver terminals and ensure good communication performance, and a communication channel changing method of the wireless communication terminal.
2. Description of the Related Art
Short distance radio communication standards, such as Bluetooth technology, have recently attracted a lot of attention from the wireless communication industry. Bluetooth, for example, allows bidirectional wireless communications among digital devices in real time by wirelessly connecting mobile phones, computers, and personal digital assistants (PDA) with other phones, computers, PDA's, and appliances in homes or offices which are within 10˜100 m of each other. Frequency bands of Bluetooth range from 2.402˜2.480 GHz which corresponds to the Industrial, Scientific, and Medical (ISM) bands of 2.4 GHz.
When a transmitter terminal and a receiver terminal communicate with each other wirelessly through Bluetooth technology, the pair of the transmitter terminal and the receiver terminal can be a mobile terminal and a wireless headset, a computer and a wireless headset, a computer and a peripheral, and the like.
Since interference between the receiver terminals is possible at a short distance, Bluetooth uses a frequency hopping method which is a kind of spread spectrum method. The frequency hopping method, which changes the frequencies at random, defines 79 frequency bands by dividing the frequency bandwidth by 1 MHz in the Bluetooth band of 2.402˜2.480 GHz and converts frequency bands to transmit signals in order to prevent interference between the receiver terminals. The frequency band conversion is carried out 1600 times per one second.
Usually, one receiver terminal is connected to one transmitter terminal for radio communications. At the initial communication, the transmitter terminal matches the channel between the transmitter terminal and the receiver terminal by sending radio signals to the receiver terminal in a preset channel. The channel is a kind of code formed through the frequency hopping, and the channel can be set based on the order in which the 79 frequency bands are converted. For instance, if the divided frequency bands are referred to as 1st through 79th bands, the channel 1 can sequentially hop the 1st through 79th bands, and the channel 2 can hop through the 5th band, the 29th band, the 17th band, and the 3rd band.
Additionally, besides advancements in short distance radio communication, ultra-wideband wireless communication is also under development using the ultra-wideband frequency band of 3.1˜5.1 GHz. The ultra-wideband wireless communication transmits and receives communication signals primarily using on-off keying (OOK) modulation which transmits and receives digital signals as ON and OFF. When the OOK modulation is adapted, to prevent the interference with other transmitter terminals, multiple channels are generated by dividing the frequency band of 3.1˜5.1 GHz to a plurality of frequency bands and the transmitter terminal and the receiver terminal communicate with each other using the selected channel of the divided bands. However, in the case that a transmitter terminal 1 and a receiver terminal 1 wirelessly communicate with each other using an arbitrary channel and a transmitter terminal 2 and a receiver terminal 2 enter communications using the same arbitrary channel within the interference range, radio communication failure occurs both between the transmitter terminal 1 and the receiver terminal 1 and between the transmitter terminal 2 and the receiver terminal 2.
Problems in the OOK scheme arise when the same channel is used by more than one pair of terminals to communicate with each other. To prevent this, when another transmitter terminal and another receiver terminal enter the radio communication range being used by a transmitter terminal and a receiver terminal, the channel can be changed automatically.